Recent increasing consumption of energy has facilitated development of solar cells capable of converting solar energy into electric energy.
Particularly, CuInGaSe (CIGS) solar cells are common, which are PN hetero junction devices having a substrate structure constituted by a glass substrate, a metal back electrode layer, a p-type CIGS light absorption layer, a high resistance buffer layer, and an n-type window layer.
Much research is now being conducted to improve the performance of such solar cells.